Saito was, of course, very close to the Founder. On the other hand:
Is not quite right. ...which is still quite good, but quite a long way from daily.
On a personal level I have to agree we you, at least partially.
My view on it is that Saito sensei was a pure product of O sensei's teaching from A to Z. And despite everything, he was probably amaong all students one of the few who had the closest relationship with M. Ueshiba. in French language "quotidien" has the added notion of familiarity, closeness, personal, close relationship, intimate, I guess this was worth being mentionned.
Besides, a quantitative centered approach may be not the most relevant view, after all there must have been some folks in Iwama who came training with O sensei every evening in the dojo, can it be said they received or understood more because of the quantity?
Somehow the 23 years span is an Iwama common place/meme that has been used often as some kind of proof or sign of some kind of "superior" transmission. In itself the figure is surely significant but my view is that it hides (or reveals rather) the quality
of the transmission, otherwise Morihiro wouldn't have been renamed and made guardian of the place O sensei called "home"...
(Cf. G. Homma in an interview or article, I can't remember)